Speaker
Dr
Massine El Kabir
(Sapienza University of Rome)
Description
Identifying electromagnetic counterparts to neutron star mergers (Kilonovae) is crucial for multi-messenger astronomy but is made difficult by the presence of contaminants. In this work, we present an analysis of AT2025ulz: an optical candidate identified within the localization of the gravitational wave event S250818k. Despite initial spatio-temporal consistency, deep Hubble Space Telescope (HST) observations reveal a different nature. We discuss the lines of evidence identifying AT2025ulz as a probable Type IIb Supernova: the transient's evolution on the color-magnitude diagram and the host galaxy analysis, which classifies the host as an edge on star forming spiral, and discussing the offset.